1. Field of the Invention
The present invention relates generally to inspection systems. More specifically, the present invention is drawn to a video camera system for inspecting the internal surfaces of pipes or vessels having interiors with limited accessibility.
2. Description of the Related Art
In a pressurized-water, nuclear-powered, electric generating system, the heat generated by a nuclear reactor is absorbed by a primary coolant that circulates through the reactor core and is utilized to transfer heat and produce steam inside the steam generator. The steam generator usually is an upright cylindrical pressure vessel with hemispherical end sections. To balance the water level inside the steam generator, a feedwater inlet-and-ring assembly introduces new water volume to offset the water loss in the steam production cycle. The feedwater is introduced from the ring assembly through "J" nozzles. "J" nozzles, which are well known in the art, are curved pipes positioned at intervals on top of the ring assembly. Typically, the nozzles are installed by drilling out the ring assembly and welding in the "J" nozzle. The ring section is usually assembled in segmented, weld-prepared sections. This assembly technique requires that backup rings are inserted in the ring assembly to establish a reinforcing structure for supporting the weld when the ring sections are assembled. Over time, the backup rings begin to erode due to the flow and velocity of the water churning through the ring assembly. Sections of the backup ring can break away and exit through the "J" nozzles. These breakaway sections are now free to wreak havoc by banging and vibrating against the steam generator tubes causing damage or rupture. The same scenario has been documented with "J" nozzle welds which have eroded and allowed the nozzles to become loose projectiles inside the steam generator.
The above scenarios have necessitated the need for efficient and effective inspection of the feedwater piping without loss of schedule, while also limiting the time for inspection to prevent unnecessary radiation dosage.
The current standard in the industry for inspection is the videoprobe. There are, however, inherent problems in its use. Videoprobes are relatively expensive, difficult to use, easily broken, costly to repair, and inspections are time consuming, using up radiation dosage. Also, the supply and repair are monopolized by a small number of companies. Videoprobes also magnify the viewed subject many times its size, depending on the distance the probe is from the viewed subject. Low lighting levels require that the viewed piping section be no more than 1-2 inches from the probe's camera and orientation of the probe in the piping interior is difficult to determine. Videoprobes also make no provision for interchanging camera lenses and light reflectors.
Other prior art devices for inspecting interior pipe surfaces are disclosed in U.S. Pat. No. 3,761,623 (Hara et al.), U.S. Pat. No. 4,246,604 (Hundertmark et al.), U.S. Pat. No. 4,424,531 (Elter et al.), U.S. Pat. No. 4,677,472 (Wood), U.S. Pat. No. 4,855,838 (Jones et al.), U.S. Pat. No. 5,084,764 (Day), U.S. Pat. No. 5,195,392 (Moore et al.), U.S. Pat. No. 5,457,288 (Olsson); EPO Patent 511,934, and Japanese Patent 4-188,098.
None of the above inventions and patents, taken either singularly or in combination, is seen to disclose an articulating camera system with variable lighting and interchangeable lens capability as will be described and claimed in the instant invention.